The invention relates to a device for displaying plasma discharge; in particular, the device has a columnar structure for the ornamental display of a full-motion and continuous plasma discharge.
Plasma discharges replicate the appearance of bolts of lightning in a safe and confined environment. Such plasma discharge displays are common as three-dimensional art or novelty items; in particular, in the form of a double glass spherical unit. U.S. Pat. No. 5,281,898 to the inventor herein shows an example of a spherical unit 28.
Plasma discharges result from the ionization of gas contained in an enclosed area excited by high voltage. Normally, ionized gas in an enclosed area produces a smooth laminar discharge. To achieve the intended animated lightning effect, instability must be introduced to encourage the gas to break away from the natural laminar flow. Adulterants in traces of 5-20 parts per million are added to the gas of prior art display units to create active and unstable ionized gas (or plasma discharge). Adulterants such as nitrogen and oxygen may be used. Prior art display units require a delicate balance of gas mixture to achieve instability. Another inherent drawback of adding adulterants to non-inert gases is that it disadvantageously reduces the lifetime of the active display as the sputtering of the electrodes slowly pumps the impurities out, leaving the display with reduced or no activity.
Another disadvantage of prior art plasma discharge display units is the usually hyperactive plasma discharge that constantly skips around in the enclosed area. In conjunction with this hyperactivity is a buzzing noise, which together decrease the overall aesthetic of the display.
Therefore, there is a need for a plasma discharge display unit that produces a full motion and continuous plasma discharge that is active (but not hyperactive) without the addition of adulterants and with reduced noise.
The invention provides a device for displaying active plasma discharge having a full motion and being continuous without the addition of adulterants and with minimal operating noise.
The plasma discharge display unit of the present invention provides a unique chamber construction where ionized gas travels to produce a full motion and continuous plasma discharge without the addition of adulterants for activity.
The device for displaying plasma discharge of the present invention comprises a generally elongated body having a cylindrical upper portion and a generally spherical lower portion to form a single wall columnar chamber for gases to be ionized. The cylindrical and spherical portions are axially aligned. Two electrodes connected to a power source are at opposite ends of the columnar chamber, tangentially located at the upper and lower ends and orthogonal to the longitudinal axis.
In operation, plasma discharge is generated at the electrode located at the bottom end. Due to the generally spherical lower portion, ionized gas is deflected from going straight up towards the upper end such that the plasma discharge appears to originate from varying departure sources at the bottom end of the lower portion. In combination with the heat generated by the plasma discharge in the chamber, the plasma discharge is able to maintain a continuous plasma discharge from the bottom to the upper ends. The curved inner surfaces of the upper and lower portions allow electrostatic attraction of the ionized gas to deflect to generate an active plasma discharge.
At least two sources of instability are introduced by the configuration of the columnar chamber of the present invention to provide an active display of plasma discharge without the addition of adulterants.